An electronic camera that performs photography using an image sensor generally is provided with an optical low-pass filter in order to prevent occurrences of moire fringes. As such an optical low-pass filter there has been known an optical low-pass filter that performs image separation utilizing the diffracting action of a diffractive grating of a phase shift type that includes a transparent substrate formed of an uneven relief surface on the surface thereof (see Patent Reference 1).    [Patent Reference 1] Japanese Laid-Open Patent Publication No. H06-148572